﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Web;
using System.Net;
using System.IO;
using System.Drawing;

namespace Helper
{
    public class ImageHelper
    {
        public static void OutputImg(string pathImageFrom, int width, int height)
        {
            string pathImageTo = "";

            string originalImagePath = pathImageFrom;
            string thumbnailPath = pathImageTo;


            System.Drawing.Image originalImage = null;
            if (!pathImageFrom.ToLower().StartsWith("http"))
                originalImage = System.Drawing.Image.FromFile(AppDomain.CurrentDomain.BaseDirectory + "" + originalImagePath);
            else
            {
                originalImage = null;
                WebRequest wreq = WebRequest.Create(pathImageFrom);
                wreq.Timeout = 10000;//超时时间
                HttpWebResponse wresp = (HttpWebResponse)wreq.GetResponse();
                using (Stream s = wresp.GetResponseStream())
                {
                    originalImage = System.Drawing.Image.FromStream(s);
                }
            }

            int w1 = originalImage.Width, h1 = originalImage.Height;
            if (width != 0 && height != 0)
                if (w1 > width) height = width * h1 / w1;
                else if (h1 > height) width = w1 * height / h1;
            int towidth = width;
            int toheight = height;
            int x = 0;
            int y = 0;
            int ow = originalImage.Width;
            int oh = originalImage.Height;
            string mode = "Cut";
            switch (mode)
            {
                case "HW"://指定高宽缩放（可能变形）　　　　　　　　
                    break;
                case "W"://指定宽，高按比例　　　　　　　　　　
                    toheight = originalImage.Height * width / originalImage.Width;
                    break;
                case "H"://指定高，宽按比例
                    towidth = originalImage.Width * height / originalImage.Height;
                    break;
                case "Cut"://指定高宽裁减（不变形）　　　　　　　　
                    if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                    {
                        oh = originalImage.Height;
                        ow = originalImage.Height * towidth / toheight;
                        y = 0;
                        x = (originalImage.Width - ow) / 2;
                    }
                    else
                    {
                        ow = originalImage.Width;
                        oh = originalImage.Width * height / towidth;
                        x = 0;
                        y = (originalImage.Height - oh) / 2;
                    }
                    break;
                default:
                    break;
            }
            //新建一个bmp图片
            System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

            //新建一个画板
            Graphics g = System.Drawing.Graphics.FromImage(bitmap);

            //设置高质量插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //清空画布并以透明背景色填充
            g.Clear(Color.Transparent);

            //在指定位置并且按指定大小绘制原图片的指定部分
            g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
              new Rectangle(x, y, ow, oh),
              GraphicsUnit.Pixel);

            try
            {
                //以jpg格式保存缩略图
                //bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
                //HttpContext.Current.Response.ClearContent();
                //  HttpContext.Current.Response.Clear();
                //   HttpContext.Current.Response.ContentType = "image/jpeg";
                //bitmap.Save(HttpContext.Current.Response.OutputStream, System.Drawing.Imaging.ImageFormat.Jpeg);
                //HttpContext.Current.Response.End();

                using (MemoryStream ms = new MemoryStream())
                {
                    bitmap.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                    HttpContext.Current.Response.ContentType = "image/jpeg";
                    HttpContext.Current.Response.BinaryWrite(ms.ToArray());
                }

            }
            catch (System.Exception e)
            {
                throw e;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }
        }

    }
}
